# Rapid processing of 85Kr/Kr ratios using Atom Trap Trace Analysis

## TL;DR

This paper introduces a rapid and efficient method using Atom Trap Trace Analysis to measure 85Kr/Kr ratios, significantly increasing throughput and reducing measurement time from 48 hours to about 4 hours per sample.

## Contribution

The authors developed a new ATTA-based technique that boosts sample throughput for 85Kr/Kr measurements by over tenfold, enabling faster groundwater dating.

## Key findings

- Measurement throughput increased to 6 samples per 24 hours.
- Achieved 3-5% relative uncertainty in 4 hours per sample.
- Reduced measurement time from 48 hours to approximately 4 hours.

## Abstract

We report a methodology for measuring 85Kr/Kr isotopic abundances using Atom Trap Trace Analysis (ATTA) that increases sample measurement throughput by over an order of magnitude to 6 samples per 24 hours. The noble gas isotope 85Kr (half-life = 10.7 yr) is a useful tracer for young groundwater in the age range of 5-50 years. ATTA, an efficient and selective laser-based atom counting method, has recently been applied to 85Kr/Kr isotopic abundance measurements, requiring 5-10 microliters of krypton gas at STP extracted from 50-100 L of water. Previously a single such measurement required 48 hours. Our new method demonstrates that we can measure 85Kr/Kr ratios with 3-5% relative uncertainty every 4 hours, on average, with the same sample requirements.